Compositions having isocyanate functional components are utilized in a variety of useful products such as adhesives, molded products and foams. Such compositions are utilized in construction, vehicle manufacture, assembly of electronic subassemblies and devices, toys and the like. The adhesives are used to bond substrates together and have found widespread use because they allow for reasonable processing conditions and exhibit good adhesion to many substrates. One common use of such compositions is to bond glass, often in the form of windows, into structures. Two-part polyisocyanate based adhesives comprise, in one part, a polyisocyanate or an isocyanate functional prepolymer and in a second part a curing agent and catalyst for the reaction of the curing agent with isocyanate groups. The curing agent is a compound having on average more than one active hydrogen atom, for instance an amine or hydroxyl moiety. Two part adhesives are often used for bonding parts to together or to other structures, for example bonding trim parts to vehicles or bonding replacement windows into vehicles. Examples of such adhesive systems include those disclosed in U.S. Pat. No. 7,892,395; US 2009/0044907; U.S. Pat. No. 6,965,008; EP 1433802 and EP 1578834, all incorporated herein by reference in their entirety. The adhesive starts to cure when the two parts are contacted. Two-part adhesives have the advantage that they cure much faster than one-part adhesives.
Manufacturers desire to handle products as soon as possible to enhance the productivity of their plants, as there is a need to move parts and to place loads on adhesive systems as soon as possible. Adhesives which have a good green strength shortly after application are needed. Adhesives are needed that exhibit longer open times, the time from application of the adhesive to a substrate until the adhesive can no longer adhere to another substrate.
What is needed is an adhesive system which exhibits good green strength, rapid cure rates and allows substrates to be handled shortly after application of the adhesive system.